In the technical field of display device, flat display devices such as Liquid Crystal Display (LCD) and Organic Light-Emitting Diode (OLED) display device have gradually replaced Cathode-Ray Tube (CRT) display device. The OLED display device has many advantages, such as self light-emitting, with a low driving voltage, a high light-emitting efficiency, a short response time, a high definition and a high picture contrast, nearly 180° viewing-angle, a wide operating temperature range, and so on. Moreover, in the OLED display device, flexible display and full color display with large area can be realized. Therefore, the OLED display device is widely used in mobile phone screen, computer screen, and full color TV, and is considered as one kind of display device with the greatest development potential in the industry.
Kodak Co. of American first raised a sandwich type organic electroluminescent component in U.S. Pat. No. 4,769,292 in 1987, which drew wide attention in the world. Kodak Co. first introduced a hole transmission layer in U.S. Pat. No. 4,885,211 two years later, which is a key point in OLED component design. Hence, a research boom on OLED began. Since OLED has the advantages of self light-emitting, in solid state, and with a wide viewing-angle and a high response speed, it has a broad application prospect in flat display device. OLED is even considered as a new generation of flat display product after LCD and Plasma Display Panel (PDP). In order to prevent quenching of the OLED component resulted from slanting of a light-emitting center to anode or cathode thereof, a carrier injection layer and a carrier transmission layer are further introduced based on the simple sandwich type component, and a multi-layered OLED component which is commonly seen now is gradually formed. As shown in FIG. 1, the OLED component comprises a substrate 1, an Indium Tin Oxide (ITO) transparent anode 2 that is arrange on the substrate 1, a hole injection layer 3 that is arrange on the ITO transparent anode 2, a hole transmission layer 4 that is arrange on the hole injection layer 3, a light-emitting layer 5 that is arrange on the hole transmission layer 4, an electron transmission layer 6 that is arrange on the light-emitting layer 5, an electron injection layer 7 that is arrange on the electron transmission layer 6, and a cathode 8 that is arrange on the electron injection layer 7. In order to improve a light-emitting efficiency of the component, the light-emitting layer is generally arranged as a host-guest doping system.
An OLED comprises an anode, an organic light-emitting layer, and a cathode that are formed on a substrate in sequence. The biggest defect of OLED is that OLED has a short lifetime, which is the biggest problem restricting the development of OLED industry. The reason for the short lifetime of OLED is that the organic material which constitutes the anode, the cathode, and the light-emitting layer of OLED component is highly sensitive to pollutants, aqueous vapor, and oxygen in the air. Electrochemical corrosion on OLED would easily occur in an aqueous vapor and oxygen containing environment, and thus the OLED component would be damaged. Therefore, OLED should be packaged in an effective manner so as to prevent aqueous vapor and oxygen from entering thereinto.
There are many methods for OLED packaging, such as desiccant packaging, ultraviolet (UV) adhesive packaging, UV adhesive and fill adhesive packaging, and frit adhesive packaging. The UV adhesive packaging technology is the earliest and the most commonly used OLED packaging technology and has the following advantages. According to the UV adhesive packaging technology, no solvent or a small amount of solvent is used, and thus the pollution of solvent on the environment can be reduced; a power consumption thereof is low, and solidification can be performed at a low temperature, which is applicable for a material sensitive to UV; a solidification speed thereof is high and can be used in a high speed production line; and a solidifying equipment thereof occupies a relatively small area. However, during UV adhesive packaging procedure, a sealant used therein is an organic material, and the molecular pinholes formed after solidification are relatively large. When OLED is packaged by a traditional method, aqueous vapor and oxygen would easily penetrate into the sealed space through the pinholes due to the solidification defect of the sealant, such as porosity thereof, and a weak binding strength thereof with the substrate and the packaging cover. As a result, the performance of the OLED component would deteriorate rapidly, and the lifetime thereof would be shortened.
Therefore, the OLED component should be packaged in an effective manner, so that a good sealability in the OLED component can be ensured, and a contact of the OLED component and aqueous vapor as well as oxygen in external environment can be reduced as much as possible, which is very important for the stability of the performance of the OLED component and prolonging the lifetime thereof. In order to achieve a better package effect, the package structure and package method in the prior art should be further improved, so that aqueous vapor and oxygen can be prevented from entering into the OLED component.
Thin-film package technology is especially applicable for some OLED with a special structure for which traditional cover package method cannot be used, such as the package of flexible OLED and flexible organic solar energy battery. In the thin-film package industry, the main method for improving the thin-film package effect in the industry is to use a dryer or to improve the aqueous vapor and oxygen proofing ability of the thin-film package layer as much as possible. For example, after the display component is manufactured, a multi-layered organic-inorganic composite thin-film can be deposited thereon so as to prolong a diffusion route of aqueous vapor and oxygen in the thin-film. However, there is an inherent limitation for this technology. This is because that, even if multiple layers of thin-films are deposited in an alternate manner, it cannot be guaranteed that no pinhole exists therein. Aqueous vapor and oxygen generally enter into the OLED component through pinholes, and consequently, the OLED component would be damaged or lose its effect. In this industry, the thin-film can be deposited through a low-temperature Atomic Layer Deposition (ALD) method, whereby a thin-film with a rather small amount of pinholes can be obtained. However, in the thin-film formed by this method, oxygen can be prevented, but aqueous vapor cannot be completely prevented. The thin-film package can be used for protecting diode or component which is sensitive to external environment, such as aqueous vapor or oxygen. The following diode or component can be protected by thin-film package, i.e., organic electronic component, solar energy battery, or secondary battery, such as secondary lithium battery. Among these diode or component, the organic electronic component can be easily affected by external environment, such as aqueous vapor or oxygen.
Since the lifetime of blue phosphorescence OLED cannot meet the using requirement at present, a fluorescent material with Triplet-Triplet Annihilation (TTA) effect is used to serve as the light-emitting material of blue OLED. According to TTA effect, two triplet excitons can be annihilated into one singlet exciton, whereby the light-emitting efficiency of the component can be improved. Theoretically, a quantum efficiency of an OLED comprising a light-emitting material with TTA effect can reach 40% to 62.5%.
It is shown by related research that, a generation probability of singlet exciton through TTA effect in the component can be increased be a suitable magnetic field, while a light-emitting intensity of the phosphorescence material would not be weakened. It is seemingly feasible that the magnetic material is directly used in the OLED. However, since the conductivity of magnetic material is poor, the above method is not feasible in fact.